escape extracted strings correctly

[nicksnyder]

fixes #160

[codecov]

Codecov Report

Merging #165 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #165      +/-   ##
==========================================
+ Coverage   68.97%   69.01%   +0.03%     
==========================================
  Files          28       28              
  Lines        2350     2353       +3     
==========================================
+ Hits         1621     1624       +3     
  Misses        639      639              
  Partials       90       90

Impacted Files	Coverage Δ
v2/goi18n/extract_command.go	64.44% <100%> (+0.8%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 45eb7b3...9992de0. Read the comment docs.